Gas insulated switchgear are used in medium and high voltage applications since about 50 years. The insulation gas widely used in the majority of the applications is SF6, named sulfurhexaflouride. SF6 has the disadvantage of due, having high global warming potential (GWP). According to that, it is under discussion for using other gas mixtures, and first alternative gas mixtures with acceptable dielectric parameters are already available. Such gases are for example mixtures of fluorketones and carrier gases as dry air.
As the dielectric and thermal performance of these new gases are not equivalent to SF6 and materials have to be selected, which are compatible to the new gases, the replacement of the SF6 in an installed gas insulated switchgear by the new gas mixtures is in the state of the art considered as not possible. As long as both solutions are existing in parallel, the customer needs to decide during the ordering, if he wants to buy an SF6 gas insulated switchgear or a new, eco-efficient gas insulated switchgear using an alternative gas mixture.
The decision to buy a SF6 equipment, when an alternative gas insulation is available, is not easy. On one hand, an environmental friendly gas solution is attractive for the customers, but on the other hand SF6 is a proven technology with a long term experience. So the new technology might include technical risks, which are not completely known, as there is only short term and no long term experience.
Some customers even insist on more than 2 years of experience in some reference projects, before using new technology. As gas insulated switchgear are a long term investment for 30 or 40 years, this is binding the customer on the old technology, even with a new attractive technology in reach.